This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A113168 #14 Sep 29 2023 07:09:53
%S A113168 0,1,3,6,10,15,21,28,36,45,47,51,57,65,75,87,101,117,135,137,140,144,
%T A113168 149,155,162,170,179,189,200,204,209,215,222,230,239,249,260,272,285,
%U A113168 291,298,306,315,325,336,348,361,375,390,398,407,417,428,440,453,467,482,498
%N A113168 a(n) is the sum of digits of the first n palindromes.
%H A113168 David A. Corneth, <a href="/A113168/b113168.txt">Table of n, a(n) for n = 1..10000</a>
%e A113168 First twelve base 10 palindromes are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22. Sum of their digits is 0+1+2+3+4+5+6+7+8+9+1+1+2+2 = 51, hence a(12) = 51.
%t A113168 With[{pals=Select[Range[0,500],#==IntegerReverse[#]&]},Table[ Total[ Flatten[ IntegerDigits/@ Take[ pals, n]]],{n,Length[pals]}]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 14 2016 *)
%Y A113168 Partial sums of A043269.
%K A113168 nonn,base
%O A113168 1,3
%A A113168 _Giovanni Teofilatto_, Jan 06 2006
%E A113168 Edited and extended by _Klaus Brockhaus_, Jan 06 2006